The present invention relates to a method and apparatus for laser engraving. This invention includes the process of creating casting waxes by laser engraving a three dimensional pattern into the wax itself, or into the rubber used to form the wax.
In the prior art for lost wax casting, numerous methods are also known for creating the waxes used in this well-known process. Most commonly, molding forms, commonly referred to as rubbers, are used to create the waxes by injecting molten wax into a void contained within the rubber. The rubbers are themselves created by forming them around a model made of a material such as silver that has been machined or hand-carved into the desired design. Waxes carved directly by hand are also known in the art. Throughout this document, all references to rubbers are intended to refer to molding forms used in lost-wax casting, rather than referring to the material rubber.
Regardless of the method used to create the waxes, the lost wax process encases the waxes in a plaster "investment" which hardens. The investment is placed in a furnace where the wax burns out, leaving a female cavity where the wax had been. Molten metal is then poured into the female cavity of the investment. When the molten metal cools, the investment is broken to remove the casting.
The known methods of creating the waxes for casting have several drawbacks. One problem with the known methods is the level of artistic or mechanical skill required. Machining a model used to create a rubber requires a high degree of specialized machining skills and a considerable amount of time. Hand carving a wax requires the same artistic skill and considerable time. In addition, a wax carved directly, permits the manufacture of a single unique piece, with no repeatability possible. Due to the time and skill required to create models or carved waxes, it is quite costly. While the cost of the model may be slight when distributed among a large production of identical castings, this cost is substantial for a single unique casting or for a smaller run. Therefore, unique or personalized products are unattractive to the consumer due to the prohibitive costs associated with their development. However, a market would exist for such items if the costs could be reduced to be more in line with the per piece costs associated with large runs.
Consequently, there is presently a need for a method of creating a molding form, such as a rubber or wax, which will solve the above problems. Specifically, there is a need for a method of making waxes quickly and efficiently which: (1) does not require highly specialized artistic or machining skills and (2) is cost efficient for a small item or single run items.